JPH0395718A - Magnetic recording carrier - Google Patents

Abstract

PURPOSE: To make it possible to obtain various excellent mechanical characteristics by using specific polyurethane which is soluble in tetrahydrofuran, has no isocyanate groups, has side chains and has urea groups (plural) contg. OH groups at chain terminals as a binder. CONSTITUTION: The polyurethane which is soluble in the tetrahydrofuran, has no isocyanate groups, has the side chains, has the urea groups contg. the OH groups at the chain terminals and has a mol. wt. of 40000 to 2000000 is used as the thermoplastic polyurethane. The polyurethane formed in such a manner that the ratio of the OH groups of components A to C: the NCO groups of a component D: the amino groups of a component E are 1:1.03 to 1.3:0.03 to 0.3 from A. 1mol mixture composed of polydiol having a mol. wt. of 400 to 4000 and A2) polydiol having a mol. wt. exceeding 1400 of >=10 in the molar ratio of A1 to A2, B. 0.3 to 10mol mixture composed of arom. diol and B2) straight chain diol, C. 0.05 to 0.5mol tri- or polyol, D. 1.3 to 13mol diisocyanate, E. 0.09 to 2mol aminoalcohol is used. As a result, the binder which is excellent in a mechanical behavior is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention comprises a non-magnetic carrier material and at least one magnetizable layer based on a polyurethane binder, which is firmly applied thereon. The binder relates to a magnetic recording carrier consisting of a polyurethane elastomer with urea groups at the chain ends with side chains of at least 50% by weight.

(Prior Art and Problems to be Solved) Increasingly high demands are placed on magnetic recording carriers in terms of recording and reproduction as well as aging resistance.

Binders become increasingly important to meet these demands.

Therefore, in order to improve various magnetic properties, efforts are being made to increase the packing density of the magnetic material in the layer, but this results in a decrease in the proportion of the binder in the layer. Similarly, efforts are being made to improve the signal-to-noise ratio through the use of increasingly finely dispersed, highly acicular magnetic materials. These materials are also very often surface modified to reduce aging phenomena. Measures of this kind make it extremely difficult to distribute the pigment during the dispersion process and to achieve good dispersion stability. However, the magnetic layer as a whole must be extremely flexible, highly elastic, and have high tear strength. In addition, in order to avoid the appearance of levels, it is required to further reduce the coefficient of friction and improve resistance to abrasion and abrasion. In addition, the mechanical stability of the magnetic layer must be ensured, especially in the case of high temperatures and humidity.

For the magnetic layers of data carriers (for example floppy disks), increasingly higher values of abrasion resistance are also required within a wide temperature range of 5 to 40.degree. This requires an increased use of liquid lubricant in the binder matrix as internal lubricant.

Particularly during coating preparation, low crosslinking in the fresh state and a high proportion of lubricant inside the magnet layer rather than on its surface are disadvantageous with respect to the yield of defect-free material.

If the amount of internal lubricant is increased, the adhesion between the magnet layer and the film and the toughness of the magnet layer will deteriorate due to the action of the plasticizer. This results in layer peeling during coating and an increase in the number of sludge-like surfaces in the magnetic layer. These drawbacks must again be compensated for by the binder component in the overall formulation of the magnet layer composition.

It is known that magnet layers which are subjected to strong mechanical loads contain polyurethane elastomers, which have proven advantageous as binders. West German Patent Publication No. 1106959 and West German Patent Publication No. 2753 have been found to be particularly effective.
No. 694, European Patent Publication No. 0069955 or US Pat. No. 2,899,411.

However, these polyurethanes often have drawbacks as the sole binder. In many cases, the wetting and dispersion of the pigments is adversely affected so that during the milling process, accidental sintering is only insufficiently broken down or agglomerations of pigment particles are only insufficiently avoided; Leading to poor orderliness and thus also to reduced packing density. Another disadvantage of the above polyurethane is that
The requisite elasticity is often accompanied by excessively low hardness and a tendency towards surface tack. It is therefore customary in general to combine the corresponding polyurethanes with other binders. Proposed binder combinations, such as the Phenokhi 7 resin described in German Patent No. 1295011 and the vinylidene chloride-acrylonitrile copolymer according to German Patent No. 2037605 or the combinations described in German Patent No. 2114611 Mixture of polycarbonate and polyurethane, West German Patent Publication No. 12
Combinations of polyurethane resins with pinyruchloride-pinyruacetate copolymer according to DE 82,700 or, for example, DE 2255802 or DE 22348
The combination of polyurethane elastomer and pinychloride-acrylic acid ester copolymer as described in No. 22 has good pigment partitioning properties and forms a layer with good packing density.

However, the magnetic layer obtained by dispersing magnetic particles in a binder to form a coating material and coating it on a carrier has good mechanical strength only if the adhesion is sufficient. A magnet layer that does not adhere well to the carrier will therefore already break or become detached from the carrier film after only a slight force is applied. It is extremely difficult to produce a magnetic layer that adheres well to the carrier even under high temperature and humidity. A possible but expensive solution is to apply an adhesion layer on the carrier prior to application of the magnetic layer. Many compositions of adhesion mediating layers of this type have been described. Thus, for example, US Pat. No. 4,183,976 describes the use of high molecular weight polyesters.

However, the application of the adhesive layer represents an additional burden in terms of materials, equipment and man-hours. Another drawback is that both the special process and the intermediate layer itself create sources of defects, thus potentially increasing the critical number of defects in high-quality record carriers. Therefore, we strive for an economical and simple method by which it is possible to produce defect-free magnetic layers of adhesion media, with excellent mechanical properties, which still adhere well even in particularly harsh climatic conditions. are doing.

These properties necessary for certain successful applications of magnetic recording carriers can only be achieved through the use of a combination of binders with good mechanical behavior. It is important that the binder, even with a high proportion of pigment, still exhibits strong adhesion to both the pigment surface and the carrier surface.

In this regard, various mixtures of polyurethane and polyester have been described (in particular West German Patent Publication No. 1269661, JP-A-57-15802).
No. 1 and Dutch Patent Publication No. 660072l4). According to JP-A-60-202528, low-molecular polyisocyanates, lactone polyesters having 2 to 8 primary OH groups (molecular weight 600 to 20,000)
) and a reaction initiator have been proposed.

However, the measures described are not sufficient to simultaneously meet all the above-mentioned demands placed on binder systems; moreover, a combination of polyurethane and another binder is often compulsorily necessary to achieve the individual effect. Become.

(Structure of the Invention) Therefore, the object of the present invention is to use a polyurethane which is thermoplastic, elastic and highly soluble in ethers and/or ketones and which has a high surface hardness and a high modulus of elasticity, thereby adversely affecting tear strength and spreadability. The objective was to prepare a magnetic recording carrier that would not be affected by Furthermore, there must be good adhesion between the layer and the carrier material. This high degree of mechanical load resistance must still be maintained even at high temperatures.

Another object of the invention was to form a corresponding record carrier in such a way that improved adhesion and increased strength of the magnetic layer are ensured even in the presence of large amounts of lubricant.

The present invention consists of a non-magnetic carrier material and at least one magnetic layer having a matrix of a magnetic material finely dispersed in a binder consisting of thermoplastic polyurethane of at least 50% by weight, which is applied forcefully onto the non-magnetic carrier material. The magnetic recording carrier is made of a thermoplastic polyurethane, soluble in tetrahydrofuran,
Contains isocyanate groups, has a side chain, has a urea group containing an OH group at the chain end, and has a molecular weight of 40,000 to 200,000.
A. A. 1 mol of a mixture of 1) a polydiol with a molecular weight of 400 to 4000 and A2) a polydiol with a molecular weight of more than 14000, with a molar ratio of component AI to component A2 of 10 or more B. B1) A mixture of an aromatic diol and B2) a linear diol having 2 to 10 carbon atoms0. 3 to 10 mol C. Tri- or polyol having 3 to 10 carbon atoms0.
05 to 0.5 mol D. 1.3 to 13 mol of a diisocyanate having 6 to 30 carbon atoms and E. Amino alcohol having 2 to 16 carbon atoms 0.09
From 2 moles to 2 moles, the ratio of OH groups of components A to C to NCO groups of component D to amino groups of component E is 1 to 1.03 to 1.3 to 0.0.
3 to 0.3, it has been found that when the polyurethane produced is used, it possesses the properties indicated in the problem.

The side-chained polyurethane used in the record carrier according to the invention therefore has between 4 and 30 OH groups per molecule.
In particular, there are 6 to 24, preferably 8 to 24, and they are bonded to the chain end via a urea group. In order to achieve the required mechanical properties, a molecular weight of at least 40,000 and at most 200,000 is required. Especially 50,000
150,000 to 150,000, especially 60,000 to 1,100
A molecular weight of 0.00 is suitable.

However, when the molecular weight is high, the number of OH groups exceeding 30 is disadvantageous because if the number of OH is large, there are too many side chains, making it difficult to manufacture and use. This is because too many side chains lead to agglomeration of molecules and overly cross-linked polymers. A crosslink number of 1 to 15, especially 2 to 10, with an arithmetic mean chain length of more than 10,000 leads to the target polyurethane elastomer.

Polyurethanes constructed in this way generally have a hardness according to DIN 53157 of 50 in the uncrosslinked state.
Exceeds s. Furthermore, the elastic modulus (elastic modulus according to DIN 53457) exceeds 500 NArm2 and the tear elongation (
DIN53455) is 100%, tear strength (DIN53455)
53455) exceeds 30 N/ffm.

The softening point is between 80 and 180°C.

High modulus polyurethane binders are generally not only hard and brittle, but also have poor adhesion to polyester carrier films. However, the binder contained in the record carrier according to the invention has significantly improved adhesion both to flexible polymeric substrates and to metal surfaces. High levels of mechanical properties remain maintained at high temperatures. Surprisingly, even air-conditioned storage does not adversely affect the bond strength. Furthermore, the dispersibility of the magnetic material has also been improved.

In a further embodiment of the record carrier according to the invention, the polyisocyanate is added to the dispersion consisting essentially of magnetic material and special polyurethane, but before it is applied to the carrier material. For crosslinking, a wide variety of organic ditri- or polyisocyanates or isocyanato prebolimers can be used, preferably up to 10,000 molecules per liter, preferably from 500 to 300 molecules per liter.
0 can be used. Preference is given to polyisocyanates or isocyanate prepolymers with more than two NCO groups per molecule. Polyisocyanates based on toluylene diisocyanate, hexamethylene diisocyanate or inphorone diisocyanate, which are produced by polyaddition to di- and triols or by biurenotate and incyanurate formation, have proven particularly suitable.

Particularly preferred are addition products of toluylene diisocyanate to trimethylolpropane and diethylene glycol. By incorporating the above-mentioned isocyanates in particular into the finished magnet dispersion before application to the carrier, the adhesion strength is still very significantly improved after air-conditioned storage;
Furthermore, the mechanical properties of the record carrier according to the invention can still be improved very significantly in terms of its abrasion resistance upon reducing the thermoplasticity of the magnet layer. The amount of polyisocyanate added for this purpose is generally from about 1 to 20% by weight, in particular from 4 to 15%, based on the total amount of binder.

The polyurethane which characterizes the record carrier according to the invention is composed of components known per se.

Component AI (polydiol) is polyesterol, polyetherol or polycarbonate with a molecular weight of 400 to 4000, preferably 700 to 2500.
are used. Polydiols are conveniently mostly linear polymers with two terminal OH groups. The acid number of the boridiol is less than 10, preferably less than 3. Polyesterols can be prepared simply by esterification of an aliphatic or aromatic dicarboxylic acid having 4 to 15 carbon atoms, preferably 4 to 8 carbon atoms, with an aliphatic or cycloaliphatic glycol having preferably 2 to 20 carbon atoms. Alternatively, it can be prepared by polymerizing a lactone having 3 to 10 carbon atoms. Examples of dicarboxylic acids include glutaric acid, pimelic acid,
Corkic acid, sebacic acid, dodecanoic acid, terephthalic acid, isophthalic acid and preferably adipic acid, succinic acid and terephthalic acid can be used. The dicarboxylic acids can be used individually or as mixtures. For the preparation of polyesterols, the corresponding acid derivatives can optionally be used instead of dicarboxylic acids,
It may be advantageous to use carboxylic anhydrides or carboxylic acid chlorides and the like. Examples of suitable glycols are diethylene glycol, pentanediol, decanediol-1
, 1o and 2,2.4 trimethylpentanediol-1
．． It is 5. In particular ethanediol-1,2, butanediol-1,4, hexanediol-1,6 and 2,2-dimethylpropanediol-1,3,1,4-dimethylol-cyclohexane, ■,4-diethanolcyclohexane, 1 , 4-diethanolpropane are used. Examples of lactones for polyesterol preparation include α, α
-dimethyl-β-propiolactone, butyrolactone and especially cabrolactone are suitable. Polyetherols are, for example, polytetrahydrofuran or polyglopylene oxide diol. Polycarbonates are generally constructed using hexanediol-1,6 as a substrate.

Component A2 (polydiol) has a molecular weight (NfW
) 14,000 or higher polyester is used. These products are soluble, linear thermoplastic copolymers with two terminal OH groups. These products contain aromatic components. Compatible commercial products include Dynamic
■Dynapol L type or Dupon of Nobe1 company
■PE 49,000 from company T.

As component B1, an aromatic diol, preferably bisphenol A or a derivative thereof, is used. Compatible products include, for example, Diano I[F]22 or D from Akzo.
You can do it manually with the product name ianoJ@3 3.

Number of carbon atoms forming component B2: 2 to 10, preferably 4
The linear aliphatic diols of 6 to 6 are, for example, ethanediol-1. 2,7'ropanediol-1,3, butanediol-1.4, hexanediol-1,6, pentanediol-1,5, decanediol-1,10,2-
Methyl-1,3-propanediol, 2-methyl-2-
butyl-1,3-propanediol, 2,2-dimethyl-l,4-butanediol, 2-methyl-2-1 thyl-
1. 3-7'ropanediol, hydroxypyrophosphate neobentyl glycol ester, diethylene glycol, triethylene glycol and methyldiethanolamine, 1,4-dimethylolcyclohexane, 1.4
-diethanolcyclohexane.

As the triol of component C, a compound having 3 to 10 carbon atoms, preferably 3 to 6 carbon atoms is used.

Examples of corresponding triols are glycerin or trimethylolpropane. For example, low-molecular-weight reaction products of trimethylolpropa/and ethylene oxide and/or propylene oxide are also suitable.

The presence of triols during the polyaddition leads to branching of the final product, which favors the mechanical properties of the polyurethane, as long as local crosslinking does not occur. As polyols that can be used are, for example, erythrinot, pentaerythrinot and sorbinot.

To form intermediates containing NCO groups, components A1B and C are reacted with aliphatic, cycloaliphatic or aromatic diisocyanates having 6 to 30 carbon atoms (component D). For this purpose, for example toluene-2, . 1-diisocyanate, toluene-2,6-diisocyanate, m-fluorinated diisocyanate, 4-1-1,3-fluorinated diisocyanate, 1,5-naphthylene diisocyanate}, 1.6-hexamethylene diisocyanate, 1
, 4-cyclohexylene diisocyanate and 1,5-
Compounds such as tetrahydronaphthylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, inphorone diiso7anate or mixtures thereof are suitable.

This NCO-containing intermediate product from components A to D is then reacted with component E. The latter are amino alcohols having 2 to 16 carbon atoms, preferably 3 to 6 carbon atoms, especially monoethanolamine, methylisoprobanolamine, ethylisoprobanolamine, methylethanolamine, 3 to 6 carbon atoms for polyurethaneurea elastomers containing O I-1 groups.
-aminopropanol, l-ethylaminobutanol-
2,4-methyl-4-aminopentanol-2,N-(
2-hydroxyethyl)aniline. Diolamines are particularly suitable. This is because they are added to the chain ends, doubling the number of OH in the polymer. Diethanolamine and panolamine have proven particularly advantageous. For polyurethaneurea elastomers containing O 2 H groups, monoamines such as dimethylamine, ethylpropylamine or dibutylamine are used as component E.

The ratio of components A to D is 0.00 to 0.00 to 0.00 to 0.00 to 0.0 to 0.0 to 0.0 to 0.0 to 20.0. 3 to 10 moles and triol 0.05 to 0
．． 5 mol of diisocyaner per mole of polydiol} can vary from 1.35 to 13 mol, the amount of diol used depends in part on the molecular weight of the polydiol used. However, for practical reasons it is expedient to use at least a 3% excess of diisocyanate over the amount required for complete chemical transformation of the reactants, so that the number of isocyanate groups used versus the hydroxyl groups in the reaction mixture is expedient. The ratio of the numbers is 1.03 to 1.3, preferably 1.05 to 1.15. At that time, the excess N
The CO group chemically reacts with the N}I group of the amino alcohol, so that the ratio of components (A to C):D:E is 1:1.
．． 03 to 1. 3: 0.03 to 0.3, preferably 1 + 1.05 to 1.15: 0.05 to 0.15.

The thermoplastic, elastic, 011-containing or 01-1-free polyurethane thus constituted is prepared in solution according to a two-step process, optionally with the addition of catalysts and other auxiliaries and/or additives. Created in existence. It is not possible to make these products according to solvent-free batch spreading.

The solution is processed because gel particles are formed at least in part during the material polyaddition because of the presence of the triol and the reaction of the amine and NCO groups. During solution polyaddition, the risk of localized overcrosslinking, which occurs during substance polyaddition, is generally avoided.

Two different methods are available for Futamata Wiro depending on the reaction conditions (amount of solvent, heat of reaction).

Method 1 Diisocyanate with some solvent'?
1SMJ, then components A, I3, C and optionally catalysts, auxiliaries, and additives at a temperature of 20 to 90°C, preferably 30 to 70°C, at a temperature of 0. Add to solvent over 2-5 hours. These components are reacted to the desired NCO content m and then reacted with component E in a second stage.

Method 2: In this method, all of the raw material components A to D are dissolved in some solvent to form a solution with a solid content of 15 to 50% by weight (
multiple). The solution is then heated with stirring to a temperature of 20 to 90° C., preferably 30 to 70° C., optionally after addition of the catalyst. Component E is then added in a second stage after the components have reacted to the desired NCO group content.

In the two-step method, in the first step N
Work with excess CO. In both techniques, part of the solvent can start the reaction and the remaining solvent can be added during or after the reaction.

As the solvent for polyurethane preparation, cyclic ethers, tetrahydrofuran, dioxane, etc., cyclic ketones, cyclohexanone, etc. are preferably used. Of course, depending on the field of application, polyurethane can be used with other strongly polar solvents,
It can also be dissolved in dimethylbormamide, N-methylpyrrolidone, dimethylsulfoxide or ethyl glycol acetate. Similarly, aromatic substances in the above solvent,
It is also possible to mix toluene, xylene, etc., and esters, ethyl acetate, butyl, etc.

Examples of suitable catalysts for the preparation of polyurethanes and for crosslinking reactions include: tertiary amines, triethylamine, triethylenediamine, N-methyl-pyridine and N-methyl-morpholine, metal salts, tin octoate, etc. , lead octoate and zinc stearate, and organometallic compounds, such as diptyltin dilaurate. The suitable catalyst h1 depends on the activity of the catalyst in question.

Generally from 5 to 0.0 O for each 1.00 M ffl part of polyurethane. It has proven convenient to use 3 parts by weight, preferably 0.01 to 0.1 parts by weight.

Polyurethane, which is a feature of the record carrier according to the invention, can be used as a general binder for the production of the magnetic layer.

However, in magnetic recording carriers for special applications it may be advantageous to add 5 to 50 parts by weight of the second binder component, preferably 10 to 40 parts by weight (resulting total amount of binder being 100 ftffi parts). . Physically drying binders that are included in binder mixtures with the above-mentioned special polyurethanes are known. This includes, for example, the hydrolysis of a pinylester-polymer and subsequent vinyl alcohol polymerization. - A polyvinyl formal binder made by chemical change with formaldehyde. The polyvinyl formal preferably has a vinyl formal group-containing content of at least 65 wt.
Heavy ffl%. A suitable polyvinyl formal has a vinyl alcohol group content of 5 to 13% by weight, a vinyl formal group content of 80 to 88% by weight, and a 1F content of about 1%.
．． 2 mataphenol-toluene (1:1)1
Dissolve polyvinyl formal 5F in oomt and add 20
The viscosity measured at °C is 50 to 120rnPas,
K value according to Fickentscher is 40 to 70
(1% in DMF). Also suitable for polyvinyl formal polymers are vinyl chloride diol mono- or di(meth)acrylate copolymer, which are known per se, for example, and diol-mono(or di)acrylate or di(meth)acrylate copolymer. ) Can be prepared by solution or suspension copolymerization with methacrylate. The diol mono- or di-acrylates or -methacrylates used for this purpose are acrylic acid or methacrylic acid and the corresponding molar number of aliphatic diols having 2 to 4 carbon atoms, ethylene glyfur, 1 + 4 phthanediol and preferably It is an esterification product with propanediol, where propanediol is preferably 1,3
-Propanediol 1.2 Propanediol O to 5
It consists of o weight ffl%. These fuborimers advantageously have a vinyl chloride content of 50 to 95% by weight and a diol-acrylate or -methacrylate content of 5 to 50% by weight. A particularly suitable copolymer preferably has a content of 7 to 90% by weight of vinyl chloride and 10 to 30% by weight of diol monoacrylate or diol monomethacrylate. A solution of a particularly suitable copolymer, such as vinyl chloride, propanediol monoacrylate, l-'' IJmer, in a mixture of equal volumes of tetrahydrofuran and dioxane has a viscosity of about 30 mPas at 25°C.

H. Fikentscher (Cellulos
The K value according to Echemie 1 3 (1932) p58~) is 30 to 50, preferably about 40.
1% in DMF). In addition, a phenoxy resin having a structure of the formula (in the formula, p approximately corresponds to 100) can also be used. These are, for example, the polymers described in German Patent No. 1295011. Cellulose ester binders are likewise suitable for the mixed binders mentioned above. These are esterification products of cellulose and carboxylic acids having from I to 4 carbon atoms, such as cellulose acetate, cellulose triacetate, cellulose acetopropionate, cellulose acetobutyrate, and the like.

The processing of the special side-chained polyurethane, optionally mixed with other binders and together with magnetic materials and customary auxiliaries, to form the record carrier according to the invention is carried out in a manner known per se.

Anisotropic magnetic materials include pigments known per se, such as iron(III) monoxide, finely divided magnetite, doped or undoped ferromagnetic chromium dioxide, which significantly influence the properties of the resulting magnetic layer. Or cobalt modification
Iron monoxide (Off) and ferrite and metal pigments can be used. Preference is given to acicular iron monoxide (4)
, Co-modified iron oxide 0) and ferromagnetic chromium dioxide. The particle size is generally 0.15 to 2 μm and 0.
．． Preference is given to the range 15 to 0.8 μm.

Furthermore, the magnet layer contains small amounts of additives, dispersants and/or ? ft.
It also contains agents or fillers, which are incorporated during the dispersion of the magnetic material or during the production of the magnetic layer.

Examples of additives of this type are fatty acids or isomerized fatty acids, stearic acid or its salts with metals from Groups I to II of the Periodic Table of the Elements, ampholytes, lecithin, etc. as well as fatty acid esters or waxes, silicone oils, etc. Carbon, etc. The amounts of additives are conventional per se and are generally less than 10M relative to the magnet layer.

The ratio of the amount of magnetic material to binder in the record carrier material according to the invention is from 1 to 10, in particular from 3 to 6. Due to the excellent pigment binding properties of special polyurethane, high concentrations of magnetic materials in the magnet layer are possible without deterioration of mechanical and elastic properties and without obvious compromise of application properties. This is particularly advantageous.

Non-magnetic and non-magnetizable carriers include customary rigid or flexible carriers, in particular linear polyester films such as polyethylene terephthalate, generally 4 to 200 μm 1
In particular, those having a thickness of 6 to 36 μm can be used. Recently, the application of magnetic layers on paper carriers for the purpose of intermediate data processing techniques has also become necessary; the coating material according to the invention can also be used advantageously for this purpose.

The production of the magnetic record carrier according to the invention can be carried out in known manner. The magnetic pigment dispersion made from the magnetic material and binder solution in a disperser, such as a pot ball mill or a stirrer mill, with the addition of dispersants and other additives, is optionally cross-linked with polyisocyanate. After incorporation, it is filtered and coated onto a non-magnetic carrier using a conventional coating machine, such as a line dispenser. Usually the magnetic alignment is carried out before the liquid coating mixture is dried on the carrier; the latter is conveniently carried out for 10-20°C at a temperature of 50-90°C.
It takes 0 seconds. The magnetic layer can be smoothed and consolidated in conventional machines by passage between heated abrasive rolls, optionally by application of pressure and temperature of 25 to 100°C, preferably 60 to 80°C.

During crosslinking of the binder, which may optionally be carried out additionally, it has proven to be very advantageous to carry out calendering before the crosslinking is completed. This is because OH-containing polymers can be consolidated very well in an uncrosslinked state, but in this case they do not stick. The thickness of the magnet layer is generally 0. The thickness is 5 to 20 μm, preferably 1 to 10 μm. In the case of magnetic tape manufacture, the coated film is cut lengthwise to conventional widths, often measured in inches.

The magnetic recording carriers according to the invention have improved adhesion and peel strength compared to those made using polyurethanes or polyurethane mixtures as binders according to the state of the art, together with harder suitable paint resin components. In addition, it is important that the known magnetic materials in the polyurethanes according to the invention can be easily formed into homogeneous, high-pigment dispersions using customary dispersion equipment and with very little time and effort. Additionally, polyurethane binders containing O 2 H groups cross-linked with polyisocyanates make it possible to produce improved magnetic recording carriers with simplified and shortened working methods. Another advantage is that the polymers suitable for the magnetic recording carrier according to the invention provide a magnetic layer that is stable even at high temperatures and high humidity.

EXAMPLES The parts and percentages given in the examples and comparative experiments below are by weight, unless stated otherwise.

It is assumed that the relationship between the weight department and the weight department is the same as that between de and kno.

Example 1 a) Preparation of component A: 7143 parts of polycarbonate diol (molecular weight 2000), linear copolyester (molecular weight 1.8000 -20000) 4821 copies,
632 parts of 1,6 hexanediol, ethoxylated 2
．． 2-bis(4-hydroxyphenyl)propane 273
7 parts and 80 parts of trimethylolpropane to 4,4'-
It was dissolved in 60,061 parts of tetrahydrofuran together with 3,672 parts of diphenylmethane diisocyanate and 935 parts of tolylidene diisocyanate and heated to 55°C. The components are allowed to react until a final viscosity of 7 Pas (at 60° C.) is reached. NCO content is 0.08%. Subsequently, 42,431 parts of tetrahydrofuran was added to reduce the solid content to 1
Dilute to 6.5%. At the same time diethanolamine 23
The reaction is stopped by adding 3 parts. The K value of the polymer produced was 63 when measured in a 1% dimethylformamide solution.
．． It is 9.

b) Preparation of dispersion A: A steel ball mill with a content of 6 liters was filled with 8 ky of steel balls with a diameter of 4-6 mm, with an average particle size of 0.23 μm and a length-to-thickness ratio of 4:1 to 7: 1. Coercive magnetic field strength 52k
Cobalt-modified iron oxide (A/m, specific surface area 42 nVFt)
In) 81 (1- and average particle size 0.24 μm z length-to-thickness ratio 5:1 to 8:11 coercive field strength 4 8 k
A/m, ferromagnetic chromium dioxide pigment 90I with a specific surface area of 30 mlFI and chromium oxide (as a support pigment of Carbon Planoc 8z1 with a specific surface area > 150 rrVP)
2) 45'? -, 16.5% solution of polymer 8 850y
-, 7 runs of tetrahydride/dioxane l. Vinyl chloride/vinyl acetate/vinyl urea/l/ in 1: 7-A/
- :ff poly? - (Union Carbid
25% solution 905' of VA GI-10) from company e, lecithin 22y- as a dispersant, stearic acid 1 as a lubricant.
lI1 Stearic acid methyl ester IIP and tetrahydrofuran/dioxane (1:1) mixture 1378 p
and dispersed for 120 hours.

The magnet dispersion is then filtered under pressure through a filter with a pore size of 5 μm and immediately before the subsequent application 31.55' of a 50% solution of triisocyanate consisting of 3 mol of toluylene diisocyanate and 1 mol of trimethylolpropane is added. was added while stirring, and applied to a polyethylene terephthalate film having a thickness of 15 μm. The coated film was passed through a magnetic field to align the magnetic particles, and then dried at a temperature of 6°C to 90°C. Heating roll (60℃, linear pressure 20
The magnet layer was consolidated by passing between 0 ky/cm2 and 0 ky/cm2. The thickness of the magnet layer is 4 μm. The coated film was subsequently cut into half inch width pieces to make videotape.

Example 2 a) Preparation of Polymer B The composition and preparation were carried out in the same manner as in Example 1, except that the terminating agent diethanolamine was replaced by the corresponding mole dibutylamine.

b) Loss PJj. The preparation process for B was carried out in the same manner as in Example 1b, except that Polymer B was used as the polyurethane elastomer and vinyl acetate/
Similarly, polymer B was used instead of vinyl alcohol copolymer (VAGT{ ), and chromium oxide (m) was mixed with U, O
35 2 I was substituted. Instead of 31.5 P of a 50% triisocyanate solution, 255' of the same was added.

Comparative Experiment 1 a) Preparation of Polymer C Polyester diol (molecular weight 1 ．．
000) 10237 parts, 1,4-butanediol 1
207 parts and 65 parts of human trimethylolpropane, 4.
4'-diphenylmethane diisocyaner} 6277
and 53,358 parts of tetrahydrofuran and heated to 55°C. The various components have a terminal viscosity of 2 Pas (6
(at 0°C).

The NCO group is 0.06%. Next, dilute with 71,144 parts of tetrahydrofuran to a solid content IZ of 5%.

At the same time, 190 parts of diethanolamine is added to stop the reaction. The K value of the polymer produced is 63.0, measured as a 1% dimethylformamide solution.

b) The dispersion/vLC adjustment process was carried out analogously to Example 1b, except that Polymer C was used as the polyurethane elastomer. In this case, tetrahydrone/dioxane (1) mixture 1130
9- was used.

Comparative Experiment 2 The preparation process of dispersion D was carried out in the same manner as in Example 1b, except that the polyurethane elastomer was used as DE-AS 1295011.
It was replaced by polyuretano made according to the melt condensation method described. So 12.5% of this polymer is dissolved.
ll130F and tetrahydronerane/dioxane (1
:1) Mixture 110(}!i' was used.

Comparative Experiment 3 a) Preparation of Polymer E In a heated reactor with a capacity of 150,000 parts and equipped with a stirrer and a reflux condenser, 10,714 parts of polycarbonate\diol (molecular weight 2000), 1,6-hexanediol 948 parts, ethoxylated 2,2-bis(
・Dissolve 1232 parts of 1-hydroxyphenyl)propane and 120 parts of trinotyrolpropane in 53472 parts of tetrahydrofuran together with 5640 parts of 4.4'97 22methane diisocyanate and 1262 parts of hydroxylidene isocyanate and heat to 55°C. Heat. The components are allowed to react until a final viscosity of 20 Pas (at 60° C.) is achieved. NCO content is 0.04%.

Subsequently, it is diluted with 39,230 parts of tetrahydrofuran to a solids content fi1 of 20.0%. At the same time, the reaction is stopped by adding 259 parts of diethanolamine.

The K value of the polymer produced is 63.0, measured as a 1% dimethylformamide solution.

b) Preparation of dispersion E A steel ball mill with a filling volume of 100,000 parts by volume is driven at about 40 times/min, and iooooo parts of steel balls and 1 of polymer E are added to it.
2.5% diluted solution 1'lt 16000 parts, vinyl formal 82%, vinyl acetate 12% and vinyl alcohol 6
10,000 parts of a 10% solution of polyvinylhonolemal with a value of 50 (1% DMF solution), N-Jyuzukiji-1
, 3- 675 parts of diaminodioleate, 270 parts of zinc stearate and average particle size of 0.5 μm, length-to-thickness ratio of 4
- Fill with 13,500 parts of ferromagnetic chromium dioxide face particles of 1 to 9.1 and 4,500 parts of tetrahydrofuran and disperse for 120 hours. This magnet I&Q is then heated under pressure to a diameter of 5 μm.
Filter through a filter of m. The magnetic dispersion is applied to a 20 μm thick polyethylene terephthalate film using a linear pourer according to conventional techniques, and after passing through a magnetic field, the coating is dried at a temperature of 60 to 100°C. Heating roll (7
0° C.) under pressure to consolidate and smooth the magnet layer. The resulting thickness is 5 μm. The coated film is subsequently cut into 3.81 WM width pieces to make audio tapes.

Comparative Experiment 4 Preparation of Polymer F In a heated reactor of m 150,000 volume fl 1 part equipped with a stirrer and a reflux condenser, polycarbonate 1 diol (molecules f'A 2000 ) 6726
part, linear copolyester from isophthalic acid/terephthalic acid mixture and diethylene glycol (molecules m 330
0) 4445 parts, ■,6-hexanediol 595
4. glS, 2577 parts of ethoxylated 2,2-bis(4-hydroxyphenyl)propane and 75 parts of trimethylolbronogun. 4'-diphenylmethane diisocyanate} 3772 parts and toluylidene diisocyanate 866 parts together with 5717 parts of tetrahydrofuran.
0 parts and heated to 55°C. The components have a terminal viscosity of 6.
React until Pas (at 60C). NG
The O content is 0.06%. G1 followed by tetrahydro a
Fran. 1 0 3 7 7 parts is solid content fl
Dilute to 6.5%. At the same time diethanolamine 2
Add 19 parts to stop the reaction. The polymer produced has a K value of 60.7' (measured in 1% dimethylformamide solution).

Comparative Experiment 5 Preparation of Polymer G In a heated reactor with a capacity of 750,000 g and equipped with a stirrer and a reflux cooling vessel, 6,849 parts of polycarbonate diol (molecular weight 2000), an isophthalic acid/terephthalic acid mixture, and diethylene glycol were prepared. linear copolyester (molecule m 4360)
4479i%, 606 parts of 1.6-hexanediol,
2,624 parts of ethoxylated 2,2-bis(4-hydroxyphenyl)propane and 77 parts of dimethylolpropane were mixed into 4. 4'-diphenylmethane diisocyanate} 3772 parts and toluylidene diisocyanate 866 parts together with 57820 parts of tetrahydrofuran.
Dissolve in B and heat to about 55°C. The components have a terminal viscosity of 6.
The reaction is allowed to proceed until Pas (at 60°C).

NCO content is 0.06%. Subsequently, 40,844 parts of terahydrofuran were added to the solid content f? ias%
dilute to At the same time, 223 parts of diethanolamine was added to stop the reaction. The I value of the raw polymer is 5, measured as a 1% dimethylformamide solution.
It is 9.6.

Comparative Experiment 6: Preparation of Polymer ■ (Lit 150,000 volume) In a heated reactor equipped with a stirrer and a reflux condenser, 6,351 parts of polycarbonate diol (molecular weight 2,000) were ethoxylated with terephthalic acid. 4288 parts of linear copolyester from 2.2-bis(·1-hydroxyphenyl)propane (molecular weight 1850), 562 parts of 1.6-hexanediol, ethoxylated 2.2-bis(4-hydroxyphenyl) 24,337% propane & 71 parts of [}limethylolpropane are dissolved in 55,028 parts of tetrahydrofuran along with 3,772 parts of 4'-diphenylmethane diisocyaner and 866 parts of tolylidene diisocyanate and heated to 55°C.

The components are allowed to react until a final viscosity of 7 Pas (at 6 Q°C) is achieved. NCO content is Q. 05%.

It is then diluted with 38,844 parts of tetrahydrofuran to a solids content of 16.5%. At the same time, the reaction is stopped by adding 207 N of diethanolamine. The K value of the polymer produced is 61.7, measured as a 1% dimethylformamide solution.

Compared to comparable products, the polyurethane according to the invention has a greater adhesion force A with the polyester film when the elastic modulus is comparable, and a greater elastic modulus A when the adhesive force is comparable (
Figure 1).

Adhesion measurements are carried out according to DIN 53289.

The polyurethane is then coated with polyisocyanate. The addition f+1 corresponds to the O I-I number resulting from the addition of amino alcohol during polyurethane synthesis.

The application of the polyurethane according to the invention leads to an improved degree of breakage of the dispersion (Table 1).

Table 1 Dispersion A99 Dispersion K! iC 76 A magnetic recording carrier made for the video field was recorded on a reference tape BRV84 (OdB
) The following measurements were made in comparison with: ( ]) Video level (luminance signal) Measurement of 2100% white images No. f3, Rohde and Schwarz
Measured using a Noise Voltmeter UPSF manufactured by Co., Ltd. ( ) 100
k}-{z) (2) Video signal-to-noise ratio (video-S/
N): Ratio of luminance signal to noise level of 100% white image, measured using Rohdeund Schwarz noise voltmeter UPSF (100 kHz) (3) Color signal-to-noise ratio (color S/N): Color signal to noise level ratio, Rohde and S
Measured using chwarz noise voltmeter UPSF (
100 kI-Iz3 MI{z) (4) Sustained operation in a humid environment: The cassette was subjected to continuous operation for 100 cycles of 2 hours each in a Vl{S recorder under weather conditions of 40° C. and relative humidity of 85 parts. The wear that appears on the video henode during this time is measured by μ per 1oo hour of operation.
Shown in m units.

(5) Measure the adhesion strength of the magnet layer according to ECMA Standard No. 120 No. 5.
．． Measured according to Section 11, page 6. When measuring peel strength, the tape was pulled against the film side with an acute edge at a specific angle. In this case, the tape movement is continuously measured (above the edge) up to the moment of layer separation and is continuously increased. The table movement at the time of delamination is a measure of peel strength.

The measurement results are shown in Tables 2 and 3.

Table 2 Layer adhesion [cN] Dispersion thickness A 200 Dispersion liquid C I =1 4 Minute failure liquid D 85 Dispersion liquid A +3.4 +4.3 +2.0
Normal 3 dispersion B +3.2 +4.5
+1.5 Normal 5 Dispersion D +3.6
+4.6 +2.0 Stop

[Brief explanation of drawings]

Figure 1 shows the adhesion force and elastic modulus (EModul) of polyurethane examples according to the present invention and those used in comparative experiments.
FIG.

Claims (7)

[Claims] (1) a non-magnetic carrier material and at least one magnetic layer, the matrix of which is a magnetic material finely dispersed in a binder consisting of at least 50% by weight thermoplastic polyurethane, adhered and forcefully applied thereon; In a magnetic record carrier,
As the thermoplastic polyurethane, a polyurethane with a molecular weight of 40,000 to 200,000 is used, which is soluble in tetrahydrofuran, has no isocyanate groups, has a side chain, and has urea groups containing an OH group at the chain end. , 1 mol B of a mixture of A1) a polydiol with a molecular weight of 400 to 4,000 and A2) a polydiol with a molecular weight of more than 14,000 in which the molar ratio of component A1 to component A2 is 10 or more, B1) an aromatic diol and B2) a carbon atom number of 2 to 0.3 to 10 mol C of a mixture with 10 linear diols, 0.
05 to 0.5 mol D, 1.3 to 13 mol of diisocyanate having 6 to 30 carbon atoms and E, 0.09 mol of amino alcohol having 2 to 16 carbon atoms.
From 2 moles to 2 moles, the ratio of OH groups of components A to C to NCO groups of component D to amino groups of component E is 1:1.03 to 1.3:0.0.
3 to 0.3. (2) a non-magnetic carrier material and at least one magnetic layer having a magnetic material as a matrix finely dispersed in a binder consisting of at least 50% by weight thermoplastic polyurethane, adhesively applied thereon; In the magnetic recording carrier, the thermoplastic polyurethane is soluble in tetrahydrofuran, has no isocyanate groups, has side chains, has urea groups at the chain ends, and has a molecular weight of 4,000 to 20,000.
0 polyurethane is used, which is 1 mole of a mixture of A, A1) a polydiol with a molecular weight of 400 to 4000 and A2) a polydiol with a molecular weight of more than 14000, in which the molar ratio of component A1 to component A2 is 10 or more B, B1) 0.3 to 10 mol C of a mixture of an aromatic diol and B2) a linear diol having 2 to 10 carbon atoms, 0.
05 to 0.5 mol D, 1.3 to 13 mol of diisocyanates having 6 to 30 carbon atoms and E, monoamines without OH groups having 2 to 16 carbon atoms 0
．． From 09 to 2 moles, the ratio of OH groups of components A to C to NCO groups of component D to amino groups of component E is 1:1.03 to 1.3:0.0
3 to 0.3. (3) Tetrahydrofuran-soluble polyurethane having a molecular weight of 40,000 to 200,000, having no isocyanate groups, having side chains, and having urea groups containing OH groups at the chain ends, is prepared using di-, tri- and polyisocyanate. isocyanate and isocyanate prepolymers with a molecular weight of 10,000
2. A magnetic recording carrier according to claim 1, characterized in that the crosslinking is carried out using one isocyanate selected from the group of: (4) A polyurethane with a molecular weight of 40,000 to 200,000 that is soluble in tetrahydrofuran, has no isocyanate groups, has side chains, and has urea groups at the chain ends,
3. The magnetic recording carrier according to claim 2, wherein the magnetic recording carrier is crosslinked with one isocyanate selected from the group of di-, tri- and polyisocyanates and isocyanate prepolymers having a molecular weight up to 10,000. . (5) Component B1) is a compound of formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (in the formula, the values of m and n can be 0, 1, or 2 mutually independently) Claims 1, 2, and 3 are characterized in that:
or 4. The magnetic recording carrier according to 4. (6) The terminal OH- group is more than 80% -NH-CO-NR^2-R^1-OH or ▲Mathematical formula, chemical formula, table, etc.▼ group (in the formula, R^1 is -(CH_2
)_n-, R^2 is -H, -CH_3, -(CH_2)
_n-CH_3, n means 1 to 10). The magnetic recording carrier according to claim 1 or 2, characterized in that it consists of _n-CH_3, n means 1 to 10). (7) A claim characterized in that a polyurethane soluble in tetrahydrofuran, without isocyanate groups, with side chains and with urea groups containing OH groups at the chain ends is used as the only binder. 5. The magnetic recording carrier according to 1, 2, 3 or 4.